Two methods from spider_fields. There are probably more of these
conn_holder related methods that can be removed
reappend_tables_part()
reappend_tables()
when generating a query to send to a remote server, spider generates
new aliases for all tables in the query (at least in the group_by handler).
First it walks all the expressions and create a list of new table aliases
to use for each field. Then - in init_scan() - it actually generates the
query, taking for each field the next alias from the list.
It dives recursively into functions, for example, for func(f1) it'll
go in, will see the field f1 and append to the list the new name for
the table of f1. This works fine for non-aggregate functions and
for aggregate functions in the SELECT list. But aggregate functions
in the ORDER BY are always references to the select list, they never
need to be qualified with a table name. That is, even if there is a
field name as an argument of an aggregate function in the ORDER BY
it must not append a table alias to the list. Let's just skip
aggregate functions when analyzing ORDER BY for table aliases.
This fixes spider/bugfix.mdev_29008
(was observed on aarch64, x86, ppc64le, and amd64 --rr)
When executing a query like "select id, 0 as const, val from ...", there are 3 columns(items) in Query->select at handlerton->create_group_by(). After that, MariaDB makes a temporary table with 2 columns. The skipped items are const item, so fixing Spider to skip const items for items at Query->select.
Add a system variable spider_slave_trx_isolation.
- spider_slave_trx_isolation
The transaction isolation level when Spider table is used by slave SQL thread.
-1 : OFF
0 : READ UNCOMMITTED
1 : READ COMMITTED
2 : REPEATABLE READ
3 : SERIALIZABLE
The default value is -1
Miscellaneous Spider typos
The SELECT with the INNER JOIN is executed with one of the two tables being
optimized as a constant table, which is pre-read. Spider nevertheless attempts
to push down the join to the data node. The crash occurs because the constant
table is excluded from the optimized query that Spider attempts to push down.
In order for Spider to be able to push down a join, the following conditions
need to be met:
- All of the tables involved in the join need to be included in the optimized
query that Spider pushes down. When any of the tables involved in the join
is a constant table, it is excluded from the optimized query that Spider
attempts to push down.
- All fields involved in the query need to be members of tables included in the
optimized query.
I fixed the problem by preventing Spider from pushing down queries that include
a field that is not a member of a table included in the optimized query. This
solution fixes the reported problem and also fixes other potential problems.
Author:
Jacob Mathew.
Reviewer:
Kentoku Shiba.
The problem occurred because the Spider node was incorrectly handling
timestamp values sent to and received from the data nodes.
The problem has been corrected as follows:
- Added logic to set and maintain the UTC time zone on the data nodes.
To prevent timestamp ambiguity, it is necessary for the data nodes to use
a time zone such as UTC which does not have daylight savings time.
- Removed the spider_sync_time_zone configuration variable, which did not
solve the problem and which interfered with the solution.
- Added logic to convert to the UTC time zone all timestamp values sent to
and received from the data nodes. This is done for both unique and
non-unique timestamp columns. It is done for WHERE clauses, applying to
SELECT, UPDATE and DELETE statements, and for UPDATE columns.
- Disabled Spider's use of direct update when any of the columns to update is
a timestamp column. This is necessary to prevent false duplicate key value
errors.
- Added a new test spider.timestamp to thoroughly test Spider's handling of
timestamp values.
Author:
Jacob Mathew.
Reviewer:
Kentoku Shiba.
Cherry-Picked:
Commit 97cc9d3 on branch bb-10.3-MDEV-16246
Includes Spider patches
- 062_mariadb-10.2.0.direct_join_1and3.diff
- 063_mariadb-10.2.0.direct_join_for_single_partition.diff
- Test cases from Kentoku
Allows Spider to push full joins to the Spider engine trough the
create_group_by interface.
Other things:
- Increased MYSQL_VERSION_ID to check for 10211 (latest 10.2 version)
- Fix for const_table at calling create_group_by().
Original author: Kentoku SHIBA
